1. Technical Field
The present invention relates to a table cutting machine adapted to move a cutting machine body provided with, for example, a round grind stone or a rotary blade such as saw tooth downward for carrying out a cutting operation or the like to a cut material fixed on a table.
2. Description of the Related Art
This type of table cutting machine includes a table, on which a workpiece is supported and fixed in position, and a cutting machine body vertically movably supported on the table. The cutting machine body includes an electric motor as a drive source and a circular rotary blade rotatably driven by the electric motor. In order to perform a cutting operation, with a workpiece fixed onto that table and with the cutting blade rotated, an operator moves the cutting machine body vertically downward, so that the rotary blade cuts into the workpiece.
A fence is positioned on the table in order to position the workpiece within a plane parallel to the table surface. In the case of a cutting machine having a turntable rotatably supported on a base, the fence is positioned to extend over the turntable and opposite ends of the fence is fixedly attached to the base.
In addition to a cutting machine having a cutting machine body that is simply vertically moved to perform a cutting operation, a slide-type cutting machine is known. The slide-type cutting machine has a cutting machine body that can be slid in a direction within a plane parallel to the table surface after having moved downward. Therefore, a rotary blade can cut a workpiece as it moves by a large stroke.
In general, a cutting machine body has a configuration in which a substantially upper half range of the periphery of the rotary blade is covered with a fixed cover (blade case) and a substantially lower half range of the peripheral thereof is covered with a movable cover which employs an open-close system has been disclosed. An electric motor as a drive source is arranged on the rear side of the fixed cover. The electric motor causes a spindle projecting into the fixed cover to rotate. The rotary blade is mounted to the spindle. The movable cover is gradually opened in association with the downward movement of the cutting machine body and, meanwhile, a lower portion of the rotary blade is gradually exposed and this exposed portion gradually cut into the cut material. Therefore, a maximum range of the rotary blade which is able to cut into the cut material is limited to a range exposed downward from the fixed cover in a state in which the movable cover is fully opened.
Yet, a larger cutting depth is required for some special cutting operations. In a case of cutting a so-called crown-mold material, which is a cut material used mainly as a house-building material and has widthwise ends inclined in the opposite directions from each other in terms of the thickness direction, in the widthwise oblique direction for example, since both the oblique end surfaces at the widthwise ends need to be cut at an precise angle, the cut material generally is leaned obliquely between a table and a positioning fence, is fixedly positioned, and is brought into abutment at the inclined end surfaces thereof at the widthwise ends with the upper surface of the table and a positioning surface of the fence respectively in a surface abutment state and, in this state, the table is rotated, and the rotary blade is advanced so as to cut into the material obliquely in terms of the widthwise direction, so that an angular cutting is achieved.
In order to carry out the special cutting operation as described above (for example, the cutting operation carried out for a high cut material by placing the same so as to lean obliquely between the table and the positioning fence), various technologies have been disclosed. For example, a lower end portion of the fixed cover in a range on the rear side of the spindle (the center of rotation of the rotary blade) (hereinafter, referred simply as a rear edge of the fixed cover) is recessed upward to secure a larger cutting depth in the range on the rear side, thereby enabling the above-described special cutting operation.
According to these technologies, as a result of having retracted the rear edge of the fixed cover upward, part of a cutting edge of the rotary blade is not covered completely with the movable cover, and hence a configuration in which the uncovered portion is covered by an additionally provided auxiliary cover. This type of configuration can use a link lever to open and close the auxiliary cover using the upward and downward movement of the cutting machine body or a configuration in which the auxiliary cover is turned in the closing direction by its own weight, is brought into abutment with the upper surface of the cutting material, and is relatively opened by the downward movement of the cutting machine body is employed as the opening and closing operations of the auxiliary cover employed.
However, in the case of the slide-type cutting machine, when the rear edge of the fixed cover is retraced upward to ensure a large cutting depth at a rear side region, a problem may be caused that a mount flange for mounting the rotary blade to the spindle, or the like may contact the workpiece to cause damage to the workpiece when the cutting machine body is slid by a large distance in a cutting direction.
Because no specific countermeasure has been taken in the known art, an operator must carefully control a sliding distance of the cutting machine body not to cause contact of the mount flange with the workpiece. Therefore, the known slide-type cutting device is still necessary to be improved in its operability.
Thus, there is a need in the art for a configuration that can improve the operability of a cutting machine by preventing a mounting device for mounting a rotary blade, or the like from contacting with a workpiece during a sliding movement of a cutting machine body in the case that the cutting machine body is vertically movable and can slide in a direction parallel to a surface of a table and that a lower edge of a fixed cover is retracted upward for ensuring a large cutting depth.